The craze-like zones are characterized by a high
degree of stretching of the lamellae and void
formation. Locally, an elongation ratio of lO4
may be estimated. However, the macroscopic
elongation at break is relatively low (only ca. 34%,
see Fig. 17) due to the extreme localization of the
zones. Hence, one can correlate the transition in
deformation mode with the thickness of polystyrene
layers. These results provide strong evidence for the
proposed thin layer yielding mechanism discussed in
Section 5.5.